Absorption of carbon dioxide into N-methyldiethanolamine in a high-throughput microchannel reactor

• Microporous tube-in-tube microreactor is a high-throughput device for CO2 capture.
• The high volume mass transfer coefficient and CO2 removal efficiency were achieved.
• Effects of design and operating parameters were studied to optimize the conditions.
• The alkanolamine solutions of 10 wt.% MDEA and 4 wt.% PZ were used as absorbents.
• Smaller micropore size and annular channel width led to higher mass transfer efficiency.

Global warming due to greenhouse effects is on the rise, and many efforts to reduce emissions of CO2 which is a major greenhouse gas from combustion of carbonaceous materials are being made. In this study, chemical absorption of CO2 into N-methyldiethanolamine (MDEA) solution combined with effective activator piperazine (PZ), from a gas mixture containing N2 was carried out in a high-throughput microporous tube-in-tube microchannel reactor (MTMCR). As a novel microreactor, MTMCR greatly intensifies gas–liquid mass transfer due to its large gas–liquid interfacial area. The effects of different parameters on the overall volume mass transfer coefficient and CO2 removal efficiency were investigated. The results showed that both mass transfer coefficient and CO2 removal efficiency increased with an increase in the liquid flow rate, temperature and concentration of liquid solvent. Also, the gas–liquid mass transfer efficiency increased with a decrease in the size of the micropore and annular channel of MTMCR. The volume mass transfer coefficient and CO2 removal efficiency reached 1.70 s−1 and 97%, respectively, at flow rates of 100 L/h and 5.32 L/h for gas and liquid respectively, with alkanolamine solutions containing 10 wt.% MDEA and 4 wt.% PZ.